There is no doubt the arrangements and demo's are GREAT on both of these machines.
The authenticity and separation of the Instrument's used in these demo's I feel the Audya clearly wins.
The Korg, like the Tyros 3 have a nice balance or blend of the voices used in the styles, however they have a caned sound or a synthesized sound.
I hear a better separation or LIVE sound, more like a real group of musicians playing live on a stage.
If you compare the two closely, you can hear that.
Another way to explain this,the Korg and Yamaha sound as if one microphone was used to record a group of musicians playing live on stage.
The Audya sounds like one microphone was used for EACH musician playing live on stage.
The key here, is the Audya presents a much more REAL reproduction of the instruments and separation of the instruments and a somewhat unbalanced sound.
More like listening to a live band on stage.
This gives the Audya the clear sounding edge over Roland, Korg and Yamaha.
Yes, some of the voices used on these machines are better that others.
However, I feel the total package winner, goes to the Audya!